It is known that a silver halide photographic element, after light (visible light or IR radiation) exposure, is photographically processed (e.g., developed, fixed and water washed) and then dried to remove water with which it has been impregnated during processing.
Usually, processing of photographic elements is performed in automatic processing machines (processors) comprising a developing tank, a fixing tank, a water washing tank and a drying section. Typically, processing of the photographic element involves movement of the element in a sinuous path through an array of rollers immersed in developing, fixing and washing liquids and provided in the drying section. The rollers both guide the film through the sinuous path and press liquid from the film.
In processing operations, the formation of microbiological growth in wash water of the washing tank of a photographic processor is often a problem. The accumulation of microbes (bacteria and fungi) appears in the processor as dirt and slime which foul tank walls, racks, rollers and drain lines, and can build up to such an extent as to plug drains. Recently, techniques have been proposed to reduce the amount of water used in water washing, for environmental protection, to minimize exhaustion of water resources and for enhanced economy. Such techniques are described by S. R. Goldwasser in Journal of the Society of Motion Picture and Television Engineers, vol. 64, pages 248-253, (1955) and in U.S. Pat. No. 4,336,324. However, such techniques of water-saving substantially increase the retention time of water in washing tanks and enable the proliferation of bacteria. While effective cleaning procedures can alleviate the problem to some extent, they require a great deal of time and effort.
It is known that microbiological growth in processing wash waters can be effectively controlled by the use of biocides. Particularly effective biocides for this purpose include chlorinated phenols such as p-chloro-m-xylenol, trichlorophenol and pentachlorophenol, thiazolinone compounds such as 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 1,2-benzoisothiazolin-3-one, organoarsenide compounds such as 10, 10'-oxybiphenoxyarsine, compounds releasing active halogen atoms such as sodium hypochlorite, sodium dichloroisocyanurate, 1,2-dichloro-5,5-dimethyl-hydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, 2-bromo-4'-hydroxyacetophenone, compounds releasing silver ions such as silver nitrate, silver chloride, silver acetate and silver sulfate, and quaternary ammonium compounds such as diisobutylphenoxyethyl dimethyl benzyl ammonium chloride. These compounds can be added to the washing water in any amount which is effective to retard microbiological growths. Typically, amounts of from about 1 to about 1000 milligrams of biocide per liter of washing water are employed. The addition of these biocides to the washing water is usually carried out by directly adding them to the washing water the biocide in the form of a solution, powder, tablets, granules or the like or adding the biocide to the washing water after dissolving it in an additional water. Research Disclosure 18751, November 1979, discloses a procedure for utilizing a biocide in the control of microbiological growth which comprises incorporating the biocide in a filter housing which is placed in the wash water line just prior to the point where it enters the wash tank.
Biocides in the form of tablets, in which they are admixed with proper binders, are commercially used so as not to impair the safety of the working environment since spillable liquids or powders are eliminated. U.S. Pat. No. 4,662,538 discloses a bactericidal pellet dispenser and makes reference to other patents disclosing chemical tablet dispensing devices. Such dispensing devices, however, are bulky, comprise several components and cannot readily be used as integral part of photographic processors. JP 05181252 describes an automatic developing machine for a silver halide photosensitive material, which includes equipment for supplying an antibacterial agent into the water washing tank one hour after treatment of the photosensitive material.